As the above-mentioned motion guide device, there is known a motion guide device including a track rail having a rolling surface for balls formed along its longitudinal direction, and a moving block that is assembled to the track rail through intermediation of the balls rolling on the rolling surface and has an endless circulation path for the balls. The moving block includes a block main body and a pair of lid members. The block main body has a load rolling surface that is opposed to the rolling surface of the track rail to form a load ball path for the balls, and a ball return hole for circulating the balls. The pair of lid members is fixed to both front and rear end surfaces of the block main body. The balls are circulated through the endless circulation path for the balls, which is provided in the moving block, and thus the moving block can continuously move along the longitudinal direction of the track rail.
In the motion guide device configured as described above, depending on the usage environment, foreign matters such as chips of a workpiece or refuse may adhere to the track rail. If those foreign matters enter the moving block running along the track rail, flaws may be generated in a rolling surface of the track rail, a load rolling surface of the moving block, or in the balls, or abrasion of those members may be accelerated. As a result, a movement accuracy of the moving block in the motion guide device may be impaired in an early stage.
For such reasons, in general, a pair of end seals is mounted to the moving block at both ends in a moving direction thereof. Each of the end seals includes a seal lip portion that comes into sliding contact with the surface of the track rail, and when the moving block moves along the track rail, the seal lip portion wipes the foreign matters adhering on the track rail off the surface of the track rail, thereby preventing the foreign matters from entering the moving block.
Further, inside the moving block, from the viewpoint of preventing foreign matters from entering particularly the load ball path for the balls, in general, a pair of inner seals is mounted to the moving block at positions opposed to the upper surface of the track rail, while a pair of side seals is mounted to the moving block at positions opposed to side surfaces of the track rail. Each of the inner seals and the side seals includes a seal lip portion provided along the longitudinal direction of the moving block, and the seal lip portion comes into sliding contact with the surface of the track rail similarly to the end seal.
The pair of end seals is fixed with fixing bolts to both end surfaces of the moving block in its moving direction, that is, outer side surfaces of the lid members, while the inner seal and the side seal are fixed to the moving block under a state in which both longitudinal ends thereof are retained by the pair of lid members. Further, as different means for fixing those inner seal and side seal to the moving block, as disclosed in Patent Literature 1, there is known means for forming recessed portions in the pair of end seals to be fixed to the moving block, and inserting the inner seal and the side seal through the recessed portions, to thereby retain the inner seal and the side seal between the pair of end seals.